Deep brain stimulation can be useful for treating a variety of conditions including, for example, Parkinson's disease, dystonia, essential tremor, chronic pain, Huntington's Disease, levodopa-induced dyskinesias and rigidity, bradykinesia, epilepsy and seizures, eating disorders, and mood disorders. Typically, a lead with a stimulating electrode at or near a tip of the lead provides the stimulation to target neurons in the brain. Magnetic resonance imaging (MRI) or computerized tomography (CT) scans can provide a starting point for determining where the stimulating electrode should be positioned to provide the desired stimulus to the target neurons. To more precisely determine the target location, a recording lead with a recording electrode at or near the tip of the recording lead can be inserted into the brain of the patient, and physiological maps can be generated. Typically, the recording lead is guided to the target location within the brain using a stereotactic frame and microdrive motor system.
As the recording lead is moved through the brain, field voltages and single unit voltages are observed with the recording electrode. Observation with the electrode (i.e., physiological mapping) may include activating the target neurons to generate electrical signals that can be received by the recording electrode. The mapping approach may also include electrical stimulation via the electrode that is also used for recording. Once the position of the target neurons is determined, the recording lead can be removed and the stimulating lead inserted. The object of using the recording lead followed by insertion of the stimulating lead is to position the stimulating lead as near as possible to the target neurons. The precise insertion of the stimulating lead and positioning of the stimulating lead in the precise location indicated by the recording lead can be particularly difficult. In some instances, multiple insertions of the recording lead are used for mapping, and multiple insertions of a stimulating lead may need to occur to properly position the stimulating electrode.